| /* | |
| * Licensed to the Apache Software Foundation (ASF) under one or more | |
| * contributor license agreements. See the NOTICE file distributed with | |
| * this work for additional information regarding copyright ownership. | |
| * The ASF licenses this file to You under the Apache License, Version 2.0 | |
| * (the "License"); you may not use this file except in compliance with | |
| * the License. You may obtain a copy of the License at | |
| * | |
| * http://www.apache.org/licenses/LICENSE-2.0 | |
| * | |
| * Unless required by applicable law or agreed to in writing, software | |
| * distributed under the License is distributed on an "AS IS" BASIS, | |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| * See the License for the specific language governing permissions and | |
| * limitations under the License. | |
| */ | |
| package org.apache.nifi.provenance.journaling.toc; | |
| import java.io.Closeable; | |
| /** | |
| * <p> | |
| * Reads a Table of Contents (.toc file) for a corresponding Journal File. We use a Table of Contents | |
| * to map a Block Index to an offset into the Journal file where that Block begins. We do this so that | |
| * we can then persist a Block Index for an event and then compress the Journal later. This way, we can | |
| * get good compression by compressing a large batch of events at once, and this way we can also look up | |
| * an event in a Journal that has not been compressed by looking in the Table of Contents or lookup the | |
| * event in a Journal post-compression by simply rewriting the TOC while we compress the data. | |
| * </p> | |
| */ | |
| public interface TocReader extends Closeable { | |
| /** | |
| * Indicates whether or not the corresponding Journal file is compressed | |
| * @return | |
| */ | |
| boolean isCompressed(); | |
| /** | |
| * Returns the byte offset into the Journal File for the Block with the given index. | |
| * @param blockIndex | |
| * @return | |
| */ | |
| long getBlockOffset(int blockIndex); | |
| /** | |
| * Returns the byte offset into the Journal File of the last Block in the given index | |
| * @return | |
| */ | |
| long getLastBlockOffset(); | |
| } |